Removable key operated electrical switches are well known in the art, but generally are limited to the "on" and the "off" position of a single circuit with the "on" position at one end of the operating movement, and "off" at the other. Switches of this character are illustrated and described in U.S. Pat. No. 3,632,914 which issued Jan. 4, 1972 and 3,678,229 which issued July 18, 1972, both patents being assigned to the assignee of the present invention and this application.
Such switches perform very satisfactorily in a single circuit system, and particularly electrical systems for single power tools or other such equipments where the removed key prevents any inadvertent closing of such single circuit, but combinations of equipments such as two power tools, each with its own motor, are now being provided in industry and the cost, installation, and wiring as well as the operation of two such safety switches represents problems. The safety feature of a removable key is as important or more important to the operation of the two motor system as for the one motor to insure that only the selected motor is operated at one time and that the other motor cannot then be operated.
Other electrical circuits than those for motors are provided in dual arrangements wherein the safety of a removable key to prevent operation is equally important. In fact, the different arrangements are sufficiently varied that it is more accurate to describe the applications for the present invention as two-purpose electrical systems.
The present switch provides a single removable key for the operator to be concerned with in the selective operation of one or the other of such two-purpose electrical circuits. That key couples the removable rocker and movable carrier of the switch which in turn operate switching mechanism for two different electrical circuits one at a time. This single key is of such a configuration that it can be inserted in the rocker-carrier structure of the switch in one of two selected positions corresponding to the circuit it is desired to operate. The configuration of the single key also permits rotation thereof to a second position and reinsertion in the rocker-carrier structure in a second selected position to operate the switch and control the second circuit, thus providing the necessary safety of a removable key with greater usefulness in that a single device can operate both circuits one at a time.